Air guns, as used herein, are sound sources for marine seismic exploration for petroleum deposits. The operating components of air guns of the prior art include a firing chamber holding a charge of gas under high pressure, a two-piston shuttle assembly having a firing piston which retains the charge of pressurized gas within the firing chamber, and an operating piston positioned within an operating chamber where highly pressurized gas acts against the operating piston to maintain the shuttle assembly in a closed position until firing. A hollow shaft of the shuttle assembly interconnects the two pistons and provides for pressurized gas to flow from the operating chamber through the shaft to charge the firing chamber. The air gun is triggered using a solenoid operated valve to release high pressure air into the operating chamber actuating the shuttle assembly to cause an abrupt discharge of high pressure air from the firing chamber through discharge ports and directly into the surrounding water, the water in which the air gun is immersed.
Air guns of the prior art are normally run using an air compressor on board an exploration vessel that yields high pressure compressed air in the range of 2000 psi to 3000 psi. The air gun is towed astern. The return signals are received by an array of towed hydrophones. Air guns are relatively deep penetration sources, operating with output frequencies generally between 10 Hz to about 1200 Hz, to identify subsurface geologic layers and define the subsurface structure. The present invention provides many advantages considered significant and valuable by the inventor hereof. The inventor hereof has additional patents such as U.S. Pat. Nos. 3,379,273 4,038,630, 4,271,924, 4,599,712, 4,779,245, 5,432,757, and 8,223,591. There are also some other inventors in the same field such as Fiske, U.S. Pat. No. 4,757,482, Mayzes, U.S. Pat. No. 5,315,917, Jensen U.S. Pat. No. 7,269,099 and others in the field.